Cutting machine



Nov. 21, 1939.

D. L. SMITH CUTTING MACHINE Filed July 14, 1936 4 Sheets-Sheet llbiVENTOR #414, A M BY v ATTORNEY Nov. 21, 1939. I s rr 2,180,646 ICUTTING MACHINE Filed July 14, 1936 4 Sheets-Sheet 2 INVENTO R fi Al'TORNEY D. L.'SM|TH CUTTING MACHINE Nov. 21, 1939.

Filed July 14, 1936 4 Sheets-Sheet 3 a IIFVENTOB 6 ATTORN EY Nov. 21,1939.

7 D. L. SMITH CUTTING MACHINE 4 Sheets-Sheet 4 Filed July 14, 1936INVENTOR B-Y ATTORN-EY Patented Nov. 21, 1939 UNITED STATES CUTTINGMACHINE Donald L. Smith, Dunellen, N. J., assignor to Air ReductionCompany,

Incorporated, New York,

N. Y., a corporation of New York Application July 14,

6 Claims.

This invention relates to machines for cutting by means of a gas torch.The invention is particularly intended for cutting risers from castings,but some features of the invention are not limited to such machines.

When making castings, it is common practice to have an upwardlyextending recess in the mold into which excess metal is poured when themold is filled. This metal, which is called the riser,

allows for contraction of the casting and prevents cracks or weak placesin the casting after it has cooled.

The riser must be removed from the finished casting, however, andvarious efforts have been made to remove these risers as economically aspossible. Gas cutting torches are commonly used for the work, but it isessential that no part of the casting should be removed, and it has beennecessary to allow a margin of safety by cutting the riser a slightdistance away from its juncture with the casting. The end portion of theriser which remains on the casting after the cut is then ground away tomake the final surface as accurate as necessary for the use for whichthe casting is intended.

With cutting machines of the prior art, the time required to square up acasting in all directions, with respect to the plane of movement of thegas stream, with sufiicient accuracy to cut .30 the riser close to thecasting took so much time that it more than offset the economy whichresulted from the elimination of the grinding at the other end of theoperation. It is an object of this invention to pfovide a unitarystructure that its on the casting and can be immediately clamped inposition to move a torch across a riser and cut the riser close to itsjuncture with the casting. The cutting machine of this invention clampson a cast work-piece which has a riser extending transversely withrespect to the casting so that the work-piece is of differentcrosssection at spaced points along its length.

A more general object of the invention is to provide an improved,self-contained cutting machine for moving a torch along a definitecourse,

and especially along a straight line. One feature of the machine relatesto movable supports for the pivots of'torch-supporting links. Thesesupports shift the centers about which the links swing so that thetorch-supporting portions of the links can move in a straight lineinstead of along arcuate paths;

While machines made in accordance with this invention are primarily"intended for cutting,

; they can on: occasions be utilized for welding 1936, Serial No. 90,471

by substituting a welding torch or other instrumentality in place of thecutting torch.

Other features, objects and advantages of the invention will appear orbe pointed out as the specification proceeds.

In the accompanying drawings, forming part hereof:

Fig. 1 is an end view of a riser cutting machine embodying theinvention, the machine "being shown clamped on a casting in position tocut a user;

Fig. 2 is a front view of the structure shown in Fig. 1; v

Fig. 3 is a top planview, partly in section, showing the operatingmechanism within the machine of' Figs. 1 and 2. The torch and clamphandle are omitted in Fig. 3;

Fig. 4 is a front view of the machine, mostly in section, along the line44 of Fig. 1;

Fig. 5 is a sectional view taken on the line 5--5 of Fig. 2, but showingthe torch and its holder in elevation; and

Fig. 6 is a wiring diagram for the machine.

The machine illustrated includes a frame or housing H with two shafts I2(Fig. 2) extending through its front wall. Two outside parallel arms I4are secured to the shafts l2. The up per ends of the arms l4 areconnected by a link I5. A- torch-holder I6 is connected to the link i5,and a torch ll held in the torch-holder can be moved up and down in thetorch-holder by conventional rack and pinion adjusting mean operated bya hand-wheel I9.

The machine has clamping means for connecting it to the casting fromwhich a riser is to be cut. The clamping means includes a frame 2| towhich the-housing I I is connected. Two-downward extensions- 22, 23 ofthe clamp frame-have buttons 24 (Figs. 1 and 5) which contact with theoutside of a casting 25-, one of the-extensions 22, 23 being locatedoneach side of a riser 26 extending from the casting. The Weight of themachineis supported on the casting by arms 28 having buttons 29 incontact with the top surface of the casting 25. A pivot connection 30.joins the mid-portion of each of the arms 28 to the frame 2!.

The extension 23 is wide enoughto cover a portion of the end of thecasting 25. Buttons- 32 on the extensions 23 contact with the end faceof the casting 25, and a part of the extension 23 protrudes into thecasting to provide a bearing 34 for a shaft 35, the axis of whichextends substantially parallel to the inside Wall of the casting. Aneccentric 36 on one end of the shaft 35 is turned by the shaft 35 untilthe eccentric bears against the casting and clamps it against thebuttons 24 of the extensions 22 and 23. In order to clamp the castingagainst both extensions with substantially equal force, the eccentric ispreferably located midway between the two extensions 22, 23 of the clampframe.

The shaft 35 is turned by a hand lever 38. A latch 39 on the hand leverengages between teeth of a gear segment 49 to hold the lever 38 and theconnected shaft and eccentric in any set position. The gear segment 40is fixed to the extension 23 of the frame 2|. The latch 39 is operatedby a release lever 42 pivotally connected to the hand lever 38.

The clamping means make it possible quickly to locate the machine on thecasting in the exact position for cutting the riser. The machine withsuch clamping means is used in shops where similar castings are turnedout in quantity production. When the machine is to be used for cuttingrisers from castings of a different design, the old clamp frame isreplaced with a new one which fits the new casting and which hasabutments in position to contact with enough angularly related surfacesof the casting to locate the machine accurately in position to cut theriser. The eccentric is then operated to clamp the frame securely inposition. It is the accuracy with which the machine is located by theclamping means which makes possible cuts so close to the casting thatonly with extremely accurate surface requirements is any subsequentguiding necessary. Ordinarilysuch cuts must be made sufiiciently farfrom the casting to allow for some inaccuracy in the plane of the outwithout destroying a part of the casting.

Each of the shafts I2 is rotatably supported in an eccentric 45 securedto a shaft 4! which turns in ball bearings 48. The axes of the shafts l2and eccentrics 45'are parallel.

There is a recess in the side of each eccentric 45 within the casing Iand an inside parallel arm 49 is secured to the portion of the shaft l2which extends across the recess. The inside parallel arms 49 aredirectly behind the outside parallel arms l4 and always stay in the samerelation with the outside arms because they are secured to the sameshafts I2. The two arms secured to each shaft |2 form a composite link.

The inside parallel arms 49 are connected by an inside connecting link5| which is substantially U-shaped and has three rollers 52 (Fig. 4) onstuds extending from its front side. A plate 54 fitting a slot in thefront wall of the housing I! has parallel tracks 55 extending above andbelow the rollers 52. These rollers are not in a straight line, themiddle roller being a little lower than the end rollers. The distancebetween the tracks 55 is slightly greater than the diameter of therollers 52, so that the middle roller runs on the lower track and theend rollers run on the upper track.

The tracks extend parallel to a line through and perpendicular to theaxes of both of the shafts l2. The rollers 52 prevent the insideconnecting link 5| from moving up or down and limit it to areciprocating movement. The pivot connections 51 between the link 5| andarms 49 are limited to the same movement of translation as the link. Thepivot connections 51 would ordinarily move along arcuate paths as theangular positions of the arms 49 change, but since such movement isnotpossible the shafts I2 rotate the eccentrics 45 one way or the otherSo t at t e lower ends of the arms 49 move up or down to compensate forthe constant height of the pivots 51.

The movement of the outside parallel arms l4 (Fig. 2) is exactly thesame as that of the inside arms 49 (Fig. 4), and since the pivotconnections between the link l5 and the arms l4 are directly in front ofthe pivots 5'! they have the same rectilinear motion as those pivots.Thus the link l5 (Fig. 2) and all of the structure which it supports,including the torch ll, move with straight line motion.

The inside connecting link 5| has a ridge 69 (Fig. 5) projecting fromits rear face and extending parallel to the tracks 55 throughout thelength of the lower portion of the link 5|. Two racks 62 and 62 bearagainst the ridge 69, one rack being above the ridge and the otherbelow. Holding plates 63 fastened to the ridge extend over the rearwardfaces of the racks to hold them against transverse displacement on thelink 5|. Tongues 64 on the rearward face of the link 5| and on theforward faces of the plates 63 extend parallel to the ridge 6!) and fitinto grooves in the racks 62, 62' to hold the racks on the link, butthese tongues permit the racks to move with respect to the link in thedirection of their length.

The racks 52, 62' are made movable on the link 5| for purposes ofadjustment, and they are held in their set positions by screws 66, shownin Figs. 3 and 4. These screws thread through end plates 61 and abutagainst the ends of the racks 62 and 62'. Lock nuts hold the screws 66against displacement from vibration. The end plates 61 are fastened tothe link 5| by screws 69.

Referring again to Fig. 5, a pinion ll meshes with the upper rack 62 anda similar pinion 1| meshes with the lower rack 62'. The pinions H and IIare fixed on the same shafts with gears 12 and 72, respectively. Themechanism for driving the gears 12 and 12 is best shown in Figs. 3 and4. Small gears 14 and 14' mesh with the larger gears 12 and 12',respectively.

The gears 14 and 14' are secured to the same axles as gears 15 and 15',respectively, and these latter gears are driven by pinions 16 and 16'which are rotated by shafts extending from a reduction gearing 18. Anelectric motor 19 is connected to and drives the reduction gearing 18.

The reduction gearing drives the pinions l6 and 16' in oppositedirections so that the pinions H and H which mesh with the racks rotatein opposite directions. This difference in direction of rotation of thepinions H and 'H' is necessary because the racks are under one of thepinions and above the other.

It is possible to take up the backlash and eliminate all lost motion inboth of the gear trains, through which the motor drives the racks, bymoving either of the racks 62, 62' with respect to the other in thedirection of its length. When the motor is not running, the screws 66 ofeither rack are operated to cause a. relative movement of the racks inopposite directions. With the motor stationary such movement of theracks is possible only so long as there is backlash or lost motion inthe gearing through which the racks are driven by the motor. When allbacklash in both gear trains has been taken up, there can be no furtherrelative movement of the racks. .The screws 65 are secured in their setpositions by lock nuts.

When the machine is operated by the motor. only one of the pinions IIand 1| actually transmits power to the rack, and the other pinioncontacts with the faces of its rack teeth which it would touch ifdriving the rack in the opposite direction. If the direction of rotationof the motor is reversed, the pinion which was driving becomes the onewhich holds the racks back to prevent backlash and the other pinionbecomes the driver.

Fig. 6 shows the electric control circuitof the machine. The motor 19has a field coil 8! and a centrifugal governor 82 in series with thearmature. A resistance 83 by-passes a part of the current around thegovernor. A condenser 84 is connected in parallel with the governor toprevent sparking.

A snap-switch 86 is operated by the machine so that whenever the torchreaches either end of its stroke the blade of the switch 86 is shiftedfrom one of its contacts to the other. The snapswitch 86 is electricallyconnected with a manually-operated switch 88, as shown in Fig. 6, sothat shifting of the position of the snapswitch 86 by the machine alwaysopens the motor circuit and causes the motor to stop. Manual operationof the switch 88 to reverse its position, after the machine has beenstopped by shifting the snap-switch 86, again closes the motor circuit,but with the field current reversed so that the motor 19 runs in theopposite direction and causes the torch to come back on its returnstroke.

The snap-switch 8B is operated by a rod 98 (Figs. 3 and 4) which extendsparallel to the racks of the link 5! and is supported in bearings 9! onthe inside of the housing. The rod 9!! slides lengthwise in the bearings91 and has pins 92 on opposite sides of the operating lever 93 of theswitch 86 for shifting this lever when the rod 99 moves. The end plates61 on the link 5! strike against spaced steps 95 on the rod 9|) and movethe rod to operate the snap-switch 86 as the link 5| approaches the endof its stroke in either direction. The switch 86 and its operatingmechanism comprise automatic means for stopping the machine at the endof each stroke of the torch.

The manually operated switch 88 is supported on the housing H withinconvenient reach of an attendant. The machine can be stopped at any timeby reversing the position of the switch 88, or by shifting the rod bymeans of a handle 91 on an end of the rod which extends through the wallof the housing.

The preferred embodiment of the invention has been illustrated anddescribed, but changes and modifications can be made and some featurescan be used without others.

I claim:

1. A machine of the character described, including a housing, a shaftextending through a wall of the housing, an eccentric in which the shaftturns, said eccentric being rotatable in the wall of the housing, an armfixed on the shaft, torch-holder means supported by the arm, and guidemeans within the housing constructed and arranged to cause the eccentricto move into a definite angular position for each angular position ofthe shaft so that the torch-holder on the arm is held to a fixed course.

2. A cutting machine of the character described including a housing, twoparallel shafts extending through eccentrics in the wall of the housing,an arm connected to each of the shafts inside the housing, and anotherarm connected in the same angular position on the shaft as the insidearm, a torch-holder carried by a link between the two outside arms, alink between the arms within the housing, and guide means in the housingholding said link against turning and limiting its movement to apredetermined path.

3. In a cutting or welding machine, a housing, two parallel, rotatablesupports extending through a Wall of the housing,.a pivot shaft carriedby and rotatable in each of said supports with the axis of each shaftspaced from but parallel to the axis of its associated support, anoutside arm secured to the end of each shaft outside of the housing, aninside arm secured to each shaft directly behind-the outside arm butwithin the housing, a torch-supporting link connected to the outsidearms at adistance from their connections to the pivot shafts, a drivinglink connected to the inside arms directly behind and in alinement withthe torch-supporting link connections to the outside arms, a guide trackwithin the housing for confining the movement of the driving link to apredetermined path, and mechanism for moving said driving link back andforth in the housing to swing the arms about the axes of the pivotshafts.

4. A riser cutting machine including a housing and means for holding thehousing in position on a casting from which a riser is to be cut, aguideway on a wall of the housing, a member supported by the housing andrestrained by the guideway to a reciprocating movement, a torchholder,and links supporting the torch-holder from the housing, connectionsbetween the torchholder and reciprocating member that cause thetorch-holder to move along a path similar to that of the reciprocatingmember, and power mechanism in the housing for moving said reciprocatingmember including a rack connected to said member, a pinion meshing withthe rack and means for rotating the pinion.

5. In a cutting machine having a torch support and. means for moving thetorch support including a reciprocating member, gear teeth along thelength of said member, a motor separate from the reciprocating member,two sets of gearing between the motor and the reciprocating member withthe final gear of each set in mesh with different teeth of said member,and means for effecting a relative movement of the gear trains to takeup the play in the'gearing and eliminate lost motion in the means formoving the torch.

6. A riser cutting machine including a housing and means for holding thehousing in position on a casting, a guideway on a wall of the housing, amember supported by the housing and restrained by the guideway to areciprocating movement, a torch-holder supported by the housing,

